Method and apparatus for winding an amorphous magnetic toroidal

Abstract

A continuous ribbon of annealed amorphous magnetic core material (4) is removed from a supply spool (14) and wound into an annular cavity (6) defined by a rotating bobbin (8) within a partially assembled toroidal transformer (10). An appropriate tension on the material entering the annular cavity is created by providing a magnet (35) along a guide surface (20) between the supply spool and the annular cavity to create a drag force on the material. Slack in the material between the guide surface and the entrance gap is eliminated by lightly biasing (40) a portion of the guide surface against the core material. The amorphous magnetic core material is preferably subjected to a stress relief annealing operation in the same spiral orientation and with the same inner and outer diameters as the material will assume as the core of the toroidal transformer. To accomplish this the annealed core material is backwound from its annealing spool (44) onto the supply spool and then is wound into the bobbin. The annealing process makes the thin amorphous material quite brittle so that extra care must be taken to keep from damaging the edges. Accordingly, no edge guides are used along the path of the core material from the supply spool to the entrance gap.